Kali is black or dark blue, her tongue out, garlanded with severed heads and skirted with severed arms, standing on the white body of Shiva with her foot on his chest. Nothing about this iconography is a misreading in need of correction. Her devotees see what is there, and they call her Ma, mother.
She appears in the Devi Mahatmya from the forehead of the enraged Goddess, and her decisive act is against Raktabija, a demon each of whose fallen blood-drops becomes a new demon on touching the ground. The problem is one of multiplication, and the solution is that Kali drinks the blood before it lands and eats the copies as they come. She solves by consumption what could not be solved by force.
The theology that grew around her in Bengal takes the horror as instructive rather than incidental. Time devours everything, including the worshipper; the severed heads are read as the ego, the standing on Shiva as the priority of energy over inert consciousness, and the cremation ground as the one place where nothing can be pretended. Ramprasad Sen in the eighteenth century wrote songs to her that argue, complain and accuse, addressing her as a mother who does not answer, and they are still sung. Ramakrishna in the nineteenth century served her image at Dakshineswar and reported direct experience of her, and his account carried her into the modern Hindu mainstream and, through Vivekananda, abroad.
Colonial writing made her the emblem of everything it wanted to say about Indian religion: bloodthirsty, obscene, primitive. The thuggee literature attached her name to organised murder. Her devotees do not recognise this figure, and the atlas notes it as a fact about nineteenth-century British writing rather than about the goddess.
Her worship is strongest in Bengal, Assam and Kerala. Kalighat and Dakshineswar in Kolkata are its great centres, and Kali Puja falls on the new-moon night of Diwali.